March 9, 2015 – Current guidelines recommend adjuvant radioactive iodine therapy only for high-risk and select intermediate risk patients.
Adjuvant radioactive iodine (RAI) therapy should be considered for more intermediate-risk patients with papillary thyroid cancer (PTC), according to a recent study by DCRI researchers.
PTC is a common and increasingly prevalent form of cancer in the United States. Because survival rates are generally good for PTC patients, current guidelines recommend RAI for only high-risk and select intermediate-risk patients. The new study, conducted by the DCRI’s Michaela Dinan, PhD, and Julie Ann Sosa, MD (pictured), and published online in the Journal of Clinical Endocrinology and Metabolism, suggests that most intermediate-risk PTC patients could benefit from RAI therapy.
To examine the impact of RAI on overall survival rates in intermediate-risk PTC patients, Ruel and her colleagues used the National Cancer Database to identify all thyroid cancer patients who underwent thyroid surgery between 1998 and 2006. They then used American Thyroid Association criteria to determine which of these patients should be classified as intermediate risk. Patients with aggressive variants of PTC or more than one form of primary cancer were excluded from the analysis. After this process, a total study population of 21,870 intermediate-risk patients was identified.
Earlier research has also suggested that RAI may benefit older patients but not younger ones. To explore this issue in greater detail, the researchers conducted a subanalysis of patients 45 years of age or younger.
Of the total patient population, 15,418 (70.5 percent) received RAI therapy and 6,452 (29.5 percent) did not. In the unadjusted analysis, RAI was associated with a 29 percent reduction in risk of death.
In the subanalysis of patients 45 years old or younger, RAI reduced the risk of death by 36 percent. Patients at greater risk of death tended to be male, older, and black. Other factors associated with increased risk of death included larger tumor size, presence of lymph node metastases, positive surgical margins, and lack of RAI therapy.
This study, the researchers noted, is the first nationally representative study to address the association of RAI therapy with overall survival for intermediate-risk PTC patients. Although additional research is needed, they concluded, their findings are sufficiently strong to recommend wider use of RAI therapy in intermediate-risk patients.
In addition to Dinan and Sosa, the study’s authors included Duke’s Ewa Ruel, MD; Samantha Thomas, MS; Jennifer Perkins, MD, and Sanziana Roman, MD.